From 368db7fc5cd2e16309cc46429aa87561a2b463ef Mon Sep 17 00:00:00 2001
From: Richard T Bonhomme <tincantech@protonmail.com>
Date: Sat, 16 Apr 2022 16:57:27 +0100
Subject: [PATCH] Replace non-POSIX mktemp with POSIX mkdir and mv

mktemp was used to create temp-files but it is not POSIX and
the version shipped for Windows has known bugs.

Replace mktemp with atomic directory and file creation using mkdir
and mv, both of which are atomic.

The temporary directory "session" directory is created using mkdir
with a 32bit random number for the name.

eg: /tmp/easyrsa-temp/b01dface

The temporary file is created by moving another file into the place
of the temp-file, with a 32bit random number for the name.

eg: /tmp/easyrsa-temp/b01dface/c01dface

Signed-off-by: Richard T Bonhomme <tincantech@protonmail.com>
---
 easyrsa3/easyrsa | 73 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 49 insertions(+), 24 deletions(-)

diff --git a/easyrsa3/easyrsa b/easyrsa3/easyrsa
index 443f20a..44da8e1 100755
--- a/easyrsa3/easyrsa
+++ b/easyrsa3/easyrsa
@@ -339,18 +339,44 @@ Type the word '$value' to continue, or any other input to abort."
 	exit 9
 } # => confirm()
 
-# mktemp wrapper
-easyrsa_mktemp() {
-	[ -n "$EASYRSA_TEMP_DIR_session" ] || die "EASYRSA_TEMP_DIR_session not initialized!"
-	[ -d "$EASYRSA_TEMP_DIR_session" ] || mkdir -p "$EASYRSA_TEMP_DIR_session" ||
-		die "Could not create temporary directory '$EASYRSA_TEMP_DIR_session'. Permission or concurrency problem?"
-	[ -d "$EASYRSA_TEMP_DIR_session" ] || die "Temporary directory '$EASYRSA_TEMP_DIR_session' does not exist"
+# Create session directory atomically or fail
+secure_session() {
+	# temporary directory must exist
+	[ -n "$EASYRSA_TEMP_DIR" ] || return
+	[ -d "$EASYRSA_TEMP_DIR" ] || return
 
-	tempfile="$EASYRSA_TEMP_DIR_session/tmp.$("$EASYRSA_OPENSSL" rand -hex 3)" || return
-	printf "" > "$tempfile" || return
-	
-	echo "$tempfile"
-} # => easyrsa_mktemp
+	for i in 1 2 3; do
+		session="$(easyrsa_openssl rand -hex 4)"
+		EASYRSA_TEMP_DIR_session="${EASYRSA_TEMP_DIR}/${session}"
+		mkdir "$EASYRSA_TEMP_DIR_session" || continue
+		return
+	done
+	return 1
+} # => secure_session()
+
+# Create tempfile atomically or fail
+easyrsa_mktemp() {
+	# session directory must exist
+	[ -n "$EASYRSA_TEMP_DIR_session" ] || return
+	[ -d "$EASYRSA_TEMP_DIR_session" ] || return
+
+	for i in 1 2 3; do
+		rand="$(easyrsa_openssl rand -hex 4)" || return
+
+		shotfile="${EASYRSA_TEMP_DIR_session}/shot.$rand"
+		if [ -e "$shotfile" ]; then
+			continue
+		else
+			printf "" > "$shotfile" || return
+		fi
+
+		tempfile="${EASYRSA_TEMP_DIR_session}/temp.$rand"
+		mv "$shotfile" "$tempfile" || continue
+		printf '%s\n' "$tempfile"
+		return
+	done
+	return 1
+} # => easyrsa_mktemp()
 
 # remove temp files and do terminal cleanups
 cleanup() {
@@ -420,7 +446,7 @@ easyrsa_openssl() {
 } # => easyrsa_openssl()
 
 # Verify supplied curve exists and Always generate curve file
-verify_curve_ec () {
+verify_curve_ec() {
 	# Check that the ecparams dir exists
 	[ -d "$EASYRSA_EC_DIR" ] || mkdir "$EASYRSA_EC_DIR" || die "\
 Failed creating ecparams dir (permissions?) at:
@@ -701,6 +727,9 @@ install_data_to_pki () {
 			cp -f "${EASYRSA_PKI}/${vars_file_example}" \
 				"${EASYRSA_PKI}/${vars_file}" || return
 		fi
+
+		# Initialise temporary session for easyrsa_openssl makesafeconf
+		secure_session || return
 	;;
 	vars-setup)
 		shift ;; # ok
@@ -710,6 +739,7 @@ install_data_to_pki () {
 		die "install_data_to_pki - unknown context: $1"
 	esac
 
+
 	# Check PKI is updated - Omit unnecessary checks
 	#[ -e "${EASYRSA_PKI}/${vars_file}" ] || return
 	#[ -e "${EASYRSA_PKI}/${vars_file_example}" ] || return
@@ -2242,11 +2272,12 @@ Sourcing the vars file will probably fail .."
 	#
 	# Also, integrate a partial 'init-pki' by using 'install_data_to_pki()'
 	#
-	if [ -z "$EASYRSA_TEMP_DIR_session" ]; then
+	# If EASYRSA_TEMP_DIR_session is not set then
+	if [ -d "$EASYRSA_PKI" ]; then
+		# Temp dir session
+		secure_session || die "Temporary directory secure-session failed."
+
 		if [ -d "$EASYRSA_TEMP_DIR" ]; then
-			EASYRSA_TEMP_DIR_session="$(
-					mktemp -du "$EASYRSA_TEMP_DIR/easy-rsa-$$.XXXXXX"
-				)"
 
 			#TODO: This should be removed.  Not really suitable for packaging.
 			#set_var EASYRSA_EXT_DIR		"$EASYRSA/x509-types"
@@ -2269,14 +2300,8 @@ Sourcing the vars file will probably fail .."
 
 		else
 			# If the directory does not exist then we have not run init-pki
-			if mkdir -p "$EASYRSA_TEMP_DIR"; then
-				EASYRSA_TEMP_DIR_session="$(
-					mktemp -du "$EASYRSA_TEMP_DIR/easy-rsa-$$.XXXXXX"
-					)"
-				rm -rf "$EASYRSA_TEMP_DIR"
-			else
-				die "Cannot create $EASYRSA_TEMP_DIR (permission?)"
-			fi
+			# The temp-dir is Always created by 'install_data_to_pki'
+			: # ok
 		fi
 	fi